Dulaglutide (Trulicity) and tirzepatide (Mounjaro) are both once-weekly injections from the same manufacturer, but a generation apart. Dulaglutide is a single GLP-1 receptor agonist; tirzepatide is a dual agonist that adds GIP activity. That extra mechanism translates into substantially greater weight loss and glucose lowering for tirzepatide in trials.
At a glance
| Dulaglutide | Tirzepatide | |
|---|---|---|
| Drug class | Single GLP-1 agonist | Dual GIP + GLP-1 agonist |
| Brand names | Trulicity | Mounjaro, Zepbound |
| FDA status | Approved | Approved |
| Dosing | Once weekly injection | Once weekly injection |
| Weight loss | More modest | Substantially greater (~20%+) |
| Mechanism | GLP-1 only | GIP added to GLP-1 |
| Main side effects | GI: nausea, diarrhea | GI: nausea, diarrhea |
The bottom line
Bottom line: Tirzepatide's dual GIP/GLP-1 mechanism gives it a clear advantage in both weight loss and A1c reduction over dulaglutide. Dulaglutide remains a convenient, well-established option with good cardiovascular data. Both are approved once-weekly prescription medicines with similar GI side effects.
Frequently asked questions
Is tirzepatide better than dulaglutide?
For weight loss and glucose control, tirzepatide has produced clearly greater results in trials, thanks to its added GIP activity. Dulaglutide is still effective and convenient. Both are approved prescription drugs.
What's the difference between Trulicity and Mounjaro?
Trulicity is dulaglutide, a single GLP-1 agonist; Mounjaro is tirzepatide, a dual GIP/GLP-1 agonist. The dual mechanism is associated with tirzepatide's larger weight-loss effect.
Are they made by the same company?
Yes, both are from the same manufacturer, with tirzepatide being the newer dual-agonist successor to the GLP-1-only dulaglutide.
References
Combined peer-reviewed sources from both peptide guides. Inclusion is not endorsement.
- Gerstein HC, Colhoun HM, Dagenais GR, et al. Dulaglutide and cardiovascular outcomes in type 2 diabetes (REWIND): a double-blind, randomised placebo-controlled trial. Lancet. 2019. Peer-reviewed study
- Jendle J, Grunberger G, Blevins T, et al. Efficacy and safety of dulaglutide in type 2 diabetes: review of the AWARD phase 3 program. Diabetes Metab Res Rev. 2016. Peer-reviewed study
- Nicholls SJ, Pavo I, Bhatt DL, et al. Cardiovascular Outcomes with Tirzepatide versus Dulaglutide in Type 2 Diabetes. N Engl J Med. 2025. Peer-reviewed study
- Nicholls SJ, Bhatt DL, Buse JB, et al. Comparison of tirzepatide and dulaglutide on major adverse cardiovascular events in participants with type 2 diabetes and atherosclerotic cardiovascular disease: SURPASS-CVOT design and baseline characteristics. Am Heart J. 2024. Peer-reviewed study
- Pratley RE, Aroda VR, Lingvay I, et al. Semaglutide versus dulaglutide once weekly in patients with type 2 diabetes (SUSTAIN 7): a randomised, open-label, phase 3b trial. Lancet Diabetes Endocrinol. 2018. Peer-reviewed study
- Inagaki N, Takeuchi M, Oura T, et al. Efficacy and safety of tirzepatide monotherapy compared with dulaglutide in Japanese patients with type 2 diabetes (SURPASS J-mono): a double-blind, multicentre, randomised, phase 3 trial. Lancet Diabetes Endocrinol. 2022. Peer-reviewed study
- Jastreboff AM, Aronne LJ, Ahmad NN, et al. Tirzepatide Once Weekly for the Treatment of Obesity (SURMOUNT-1). N Engl J Med. 2022. Peer-reviewed study
- Frias JP, Davies MJ, Rosenstock J, et al. Tirzepatide versus Semaglutide Once Weekly in Patients with Type 2 Diabetes (SURPASS-2). N Engl J Med. 2021. Peer-reviewed study
- Jastreboff AM, le Roux CW, Stefanski A, et al. Tirzepatide for Obesity Treatment and Diabetes Prevention. N Engl J Med. 2025. Peer-reviewed study
- Garvey WT, Frias JP, Jastreboff AM, et al. Tirzepatide once weekly for the treatment of obesity in people with type 2 diabetes (SURMOUNT-2): a double-blind, randomised, multicentre, placebo-controlled, phase 3 trial. Lancet. 2023. Peer-reviewed study
- Zhao L, Cheng Z, Lu Y, et al. Tirzepatide for Weight Reduction in Chinese Adults With Obesity: The SURMOUNT-CN Randomized Clinical Trial. JAMA. 2024. Peer-reviewed study
- Loomba R, Hartman ML, Lawitz EJ, et al. Tirzepatide for Metabolic Dysfunction-Associated Steatohepatitis with Liver Fibrosis. N Engl J Med. 2024. Peer-reviewed study